Heat exchanger apparatus and method

ABSTRACT

A heat exchanger generally including a mass of fusible material, means for melting at least a portion of the mass of material, means for rotating the mass of material to maintain the physical integrity of the molten portion of the mass of material by centrifugal force whereby an axial passageway is formed therein, means for injecting a fluid through the rotating molten portion of the mass of material and means for injecting a working fluid through the axial passageway in the rotating molten portion of the mass of material.

United States Patent 11 1 Grey [451 July 17,1973

1 1 HEAT EXCHANGER APPARATUS AND METHOD [76] Inventor: Jerry Grey, 61 Adams Drive,

Princeton, NJ.

221 Filed: Apr. 15, 1968 21 Appl. No.2 721,376

[52] US. Cl. 165/61 Primary Examiner-Edward J. Michael Att0meyMason, Fenwick and Lawrence [57] ABSTRACT A heat exchanger generally including a mass of fusible material, means for melting at least a portion of the mass of material, means for rotating the mass of material to maintain the physical integrity of the molten portion of the mass of material by centrifugal force whereby an axial passageway is formed therein, means for injecting a fluid through the rotating molten portion of the mass of material and means for injecting a working fluid through the axial passageway in the rotating molten portion of the mass of material.

23 Claims, 8 Drawing Figures IIIIIIlIIlIIlIlI/l YIIIIIIIIIIIIIlIIIII/III/IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIA Patented July 17, 1973 3 Sheets-Sheet 1 m w WW I INVENT OR mum ATTORNEYS was 3 Sheets-Sheet 2 INVENTOR w T 7 8 m 8 m 3 L m 4 a IWILIG M l 2.0K m m w 2/ 2 .FM $0 5 7V 1k m w M W m. Wm K A e e kn w a u! 3, n N m 45 3 o 6 w Q f Y r0 i J 34 m: G w

Patented July 17, 1973 J E Rev G REY i WM ATTORNEYS Patented July 17, 1973 s Sheds-Sheet a INVENTOR BY 9 Li ATTORNEY-9 HEAT EXCHANGER APPARATUS AND METHOD This invention relates to a heat exchange apparatus and method and more particularly to a novel heat exchange apparatus and method capable of gas output temperatures beyond the limits of existing heat exchangers.

Generally, in the operation of conventional heat exchange systems in which the heat exchange mediums are fluids and solids, the working fluid to be heated is passed in heat transfer relation with the solid material at a higher temperature than the fluid. Under such conditions, the amount of heat transfer and, correspondingly, the output temperature of the working fluid primarily are dependent upon the area of heat transfer surface and the temperature differential of the working fluid and the solid material. By increasing either of these variables, the temperature of the output fluid can be increased, assuming other conditions remain the same.

In prior art heat exchange systems of the type described, the output temperature of the working fluid usually has been limited by limitations imposed by the area of heat transfer surface and available temperature differentials. Space requirements and economy normally operate to limit the area of heat transfer surface. In addition, structural failure or chemical deterioration tains, from the following description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a vertical cross-sectional view of an embodiment of the invention,

FIG. la is an enlarged fragmentary view of an electrode utilized in the embodiment illustrated in FIG. 1,

FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1,

FIG. 3 is a view similar to the view shown in FIG. 1, illustrating the embodiment in operation,

FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. 3,

of the solid heat transfer medium operates as a limitation in producing higher operating temperatures.

Accordingly, it is the principal object of the present invention to provide a novel heat exchange apparatus and method.

Another object of the present invention is to provide a novel heat exchange apparatus and method adapted to produce higher fluid output temperatures than conventional systems utilizing fluid and solid heat exchange mediums.

A further object of the present invention is to provide a novel heat exchange apparatus and method capable of utilizing a molten heat source.

A still further object of the present invention is to provide a novel heat exchange apparatus and method adapted to provide maximum thermal contact between the heat exchange mediums.

Another object of the present invention is to provide a novel heat exchange apparatus and method utilizing gas and liquid heat transfer mediums wherein maximum thermal contact between the mediums is available to provide maximum heat exchange efficiency.

Another object of the present invention is to provide a novel heat exchange apparatus and method capable of producing an output temperature of a working fluid in the order of 8,000 F. to l2,000 F.

A further object of the present invention is to provide a novel heat exchange apparatus and method utilizing a molten heat source wherein the physical integrity of the molten heat source is maintained intact during operation.

A still further object of the present invention is to provide a novel heat exchange system.

Another object of the present invention is to provide a novel heat exchange apparatus which is simple in structure, inexpensive to manufacture and economical to operate.

Other objects and advantages of the present invention will become more apparent to those persons skilled in the art to which the'present invention per- FIG. 5 is a transverse cross-sectional view of another embodiment of the invention;

FIG. 6 is a vertical cross-sectional view of an embodiment of the invention utilizing nuclear energy as a heat source, and

FIG. 7 is a cross-sectional view taken along line 77 in FIG. 6.

Briefly described, the present invention generally provides a heat exchanger comprising a mass of fusible material, means for melting at least a portion of the fusible material, means for applying a force on the mass of material when at least a portion thereof is in a molten state to maintain the physical integrity of the molten portion of the material, means for injecting a first portion of a working fluid through the portion of mo] ten material, means for passing a second portion of the working fluid along a surface of the molten portion of the material and means for discharging the heated working fluid.

In a more specific embodiment of the present invention there is provided a heat exchanger including a closed chamber, means for injecting a working fluid under pressure into the chamber and at least one rotatable unit mounted in the chamber, the unit including a rigid cylindrical outer wall and a cylindrical inner stratum of fusible material, providing an axial opening through the unit having one end thereof communicating with the interior of the chamber and the other end thereof communicable with outlet means. The outer wall and inner stratum of the rotatable unit are provided with a plurality of radial openings intercommunicating the interior of the chamber and the axial opening of the unit, defining passageways for working fluid introduced into the closed chamber. Means are provided for melting the inner portion of the inner stratum and additional means are provided for rotating the unit about its cylindrical axis whereby when the inner portion of the stratum of fusible material is in the molten state, its physical integrity will be maintained by centrifugal force while a first portion of the working fluid introduced into the chamber is injected through the radial openings and the rotating moltenmass of material, and a second portion of the fluid is injected through the axial opening of the unit.

Referring to the drawings, there is illustrated a specific embodiment of the invention. This embodiment includes a pressurized chamber 10, a heat exchange unit 1 l rotatably mounted within the pressurized chamher, a drive assembly 12 for rotating the heat exchange unit about its longitudinal axis and an electrical system 13 for heating one of the heat transfer mediums of the heat exchange unit. The pressurized chamber 10 is provided with a cylindrical wall 14 closed at both ends by end walls 15 and 16, and an inlet conduit 17 having a valve 18. A pressure gage 19 also is provided to indicate the pressure of the working fluid within thepressurized chamber.

The heat exchange unit 11 consists of a cylindrical rigid wall 20, a cylindrical inner stratum of fusible material 21 providing an axial opening 22, a rear end wall 23 and a front end wall 24. The cylindrical wall 20 is disposed coaxially and has a smaller diameter relative to the cylindrical wall 14 of the chamber to provide a cylindrical space between the heat exchange unit and the cylindrical wall 14. The rear end wall 23 is spaced from end wall and is provided with an axial opening 25 therein. Mounted across the opening 25 in the rear end wall 23 is a mounting plate 26 having a plurality of openings 27 intercommunicating the interior of the pressurized chamber with the axial opening 22 of the heat exchange unit. The front end wall 24 is spaced from the end wall 16 of the chamber and is provided with an outlet conduit 28 passing through an axially disposed opening in end wall 16. The outlet conduit 28 is connected at its outer end to a stationary conduit 29 by means of a rotary coupling 30 to intercommunicate the axial opening 22 in the heat exchange unit and the conduit 29. The outlet conduit 28 passes through axial opening 31 in end wall 16, in which there is mounted an annular seal 32 to prevent leakage of working fluid within the pressurized chamber between the end wall 16 and the outlet conduit 28. Conduits 28 and 29 and coupling 30 may require cooling by either the working fluid or an external coolant supply system.

The heat exchange unit 11 is supported within the pressurized chamber by means of axially spaced support units 33,33. Each of such units includes an annular bearing race 34 having cylindrical bearings 35 on which an end of cylindrical wall is supported, and radially disposed struts 36 rigidly interconnecting the bearing race 34 and the cylindrical wall 14 of the pressurized chamber. It will be appreciated, however, that the'heat exchange unit 11 can be mounted for rotation I within the pressurized chamber in any suitable manner.

The cylindrical rigid wall 20 of the heat exchange unit is provided with a plurality of radially disposed openings 37 about its entire periphery registered with openings 38 in the inner stratum 21 of the heat exchange unit to provide a plurality of passageways intercommunicating the interior of the pressurized chamber and the axial opening 22 of the heat exchange unit. it

.thus will be appreciated that working fluid under pressure introduced into the interior of the pressurized chamber will be caused to be injected through the heat exchange unit into the axial opening 22 by means of registered openings 37 and 38, and axially through openings 27 in mounting plate 26. The working fluid in axial opening 22 of the heat exchange unit will be discharged through outlet conduit 28 into stationary conduit 29.

The electrical system 13 primarily is employed to melt the inner portion of the stratum 21 of fusible material, and generally consists of a pair of electrodes 39 and 40, connected by suitable leads 41 and 42 to an electrical power source. The electrode 39 includes an axially disposed element 43 extending through openings in end wall 15 and mounting plate 26, and an annular element 44 having the outer periphery thereof embedded in the stratum 21 of fusible material, being connected to the axial element 43 by means of a plurality of radial elements 45. The axially disposed element 43 is supported in a bushing mounted in the opening through the mounting plate 26 and is provided with a seal engaging the wall of the opening through end wall 15 to prevent leakage of working fluid within the pressurized chamber through the element 43 and the end wall 15. The electrode 39 is provided with an internal fluid passageway 46 for receiving coolant fluid through an input conduit 47, circulating the fluid within the electrode and discharging the heated coolant into the interior of the pressurized chamber through an outlet conduit 48.

The electrode 40 at the opposite end of the heat exchange unit is similar in construction to electrode 39, and includes an axial element 49 extending from the exterior through conduits 28 and 29 into the axial opening 22, and an annular element 50 having the outer periphery thereof embedded in the inner portion of the stratum 21 of fusible material, being connected to the axial element 49 by means of radial elements 51. An annular seal 52 is provided between the axial element 49 and the end wall of stationary conduit 29 to prevent leakage of working fluid within the stationary conduit 29 and the axial element 49. The electrode 40 is provided with an internal passageway 53, as best illustrated in FIG. 1a, which communicates with the fluid supply conduit 17 by means of a feed line 54 and the interior of the closed chamber by means of an exhaust line 55 to circulate fluid through the electrode which functions as a coolant. A completely external source of coolant may also be provided to the electrodes. if convenient or necessary.

The heat exchange unit 11 is rotated about its axis by means of the drive assembly 12 which consists of a motor 56, a drive gear 57 mounted on the drive shaft of the motor, a drive belt 58 and a driven gear 59 rigidly mounted on the cylindrical section 28 of the heat exchange unit. It will be appreciated that upon operation of the motor 56 the heat exchange unit within the closed chamber will be caused to rotate about its axis. Suitable control means can be provided for the motor 56 to vary the operating speed thereof, as desired, and a suitable gear reduction unit can be provided in the drive assembly.

The heat exchange unit is cooled in a regenerative manner by means of the working fluid introduced into the unit through the inlet conduit 17. It will be seen that the fluid entering the chamber 10 will pass in heat exchange relation with the cylindrical wall 20 as it flows along the outer surface thereof and through the openings 37 into aligned openings 38 in the stratum of fusible material. The fluid entering the chamber also will pass in heat exchange relation with the end walls 23 and 24 as it flows along the outer surfaces thereof and through the openings 27 in the mounting plate 26. ln addition, as previously indicated, cool working fluid is supplied through lines 47 and 54 and circulated through the internal passageways of the electrodes 46 and 50 to cool the electrodes when they are energized.

In the operation of the embodiment illustrated in the drawings, the valve 18 is opened to permit working fluid under pressure to be introduced into the interior of the closed chamber. Initially, the closed chamber will become pressurized and the working fluid will be caused to flow through openings 27 in the mounting plate 26 and through the axial opening 22 of the heat exchanger unit to be exhausted through the cylindrical section 28. Additionally, the working fluid also will flow through the registered openings 37 and 38 of the cylindrical wall and stratum 21 of the heat exchanger into the axial section 22 and will combine with the axially flowing fluid introduced through the openings 27, to be exhausted through the cylindrical conduit 28. When the closed chamber is sufficiently pressurized and the flow rate of fluid through the heat exchanger reaches the desired level, the electrodes 39 and 40 are energized to melt the inner portion of the stratum 21 of fusible material.

During the entire operation of the device, the fluid introduced into the interior of the closed chamber will be caused to pass in heat transfer relation with the cylindrical wall 20 of the heat exchange unit to cool the wall 20, prior to being injected into the interior of the heat exchange unit through the openings 27 of the face plate 26 and the radial openings 37 in the cylindrical wall 20. The working fluid functions not only to cool the cylindrical wall 20, but also to preheat the working fluid prior to being injected into the interior of the hea exchange unit.

After the inner portion of the stratum 21 has been sufflciently melted to permit the stratum 21 to rotate free of the stationary'electrodes 43 and 44, the motor 56 is energized to transmit drive and rotate the heat exchange unit about its axis. The rotation of the heat exchange unit will cause the inner molten portion of the stratum 21 to maintain its physical integrity under the influence of centrifugal force, as best illustrated in FIG. 3. Upon initial melting of the stratum 21 and continuing through normal operating conditions, a portion of the working fluid injected into the heat exchange unit through the opening 27 will flow axially through the opening 22 in heat transfer relation with the molten portion of the stratum 21. Simultaneously, a portion of the working fluid will flow through registered openings 37 and 38 and bubble through the molten portion of the stratum 21 in heat transfer relation therewith to combine with the axial flowing fluid in the opening 22 to be exhausted through output conduit 28. The position of the liquid-solid interface 60 is stabilized by the balance between the heat generation in the heat exchanger unit and heat absorption by the flow of the working fluid through the stratum 21.

When the device is to be shut down, the motor 56 and the electrodes 43 and 44 are de-energized, while the working fluid under pressure continues to be supplied to the closed chamber of the device. The effect of such procedure is to have the working fluid under pressure continue to flow through the stratum 21 as it solidifies, thus maintaining the openings 38 upon solidiflcation of the stratum 21. The angular momentum of the heat exchange unit will cause it to continue to rotate and thus produce a sufiicient centrifugal force to maintain the structural integrity of the decreasing molten portion of the stratum 21. As the molten portion of the stratum 21 solidifies and the liquid-solid interface progresses inwardly, the openings 38 are maintained by jets of working fluid injected through the radial openings 37 in the wall 20 and the portions of the openings 38 disposed between the liquid-solid interface 60 and the wall 20.

Even assuming, however, that the openings 38 might be closed following shutdown of the device, under circumstances where the supply of working fluid is shut off prior to deenergizing the electrodes 43 and 44 and the motor 56, the subsequent energization of the electrodes upon the following start up, will melt the inner portion of the stratum 21 to cause the liquid-solid to move outwardly relative to the axis of the heat exchange unit until it communicates with the portions of the previously established openings 38, to again permit the flow of working fluid injected through the radial openings 37 in the cylindrical wall 20, through the solid and molten portions of the stratum 21.

During operation of the device as described, portions of the working fluid supply are bled off through feeder lines 47 and 54 and circulated through internal passageways 46 and 53 to cool the electrodes 39 and 40. The heated coolant is discharged through return conduits 48 and 55 into the closed chamber to be injected through the heat exchange unit in the manner previously described.

It will be appreciated that heat exchange systems can be devised to provide high output volumes by utilizing a plurality of heat exchange units 11 as described in one or more closed chambers. Referring to FIG. 5, there is illustrated another embodiment of the invention wherein a plurality of heat exchange units 11a are disposed within a single casing 10a. It will be noted that the heat exchange units 11a in the embodiment shown in FIG. 5 are similar in construction and operation to the heat exchange unit 10 described in connection with the embodiment illustrated in FIGS. 1 through 4.

Any working fluid can be used with the embodiment as described which will not react chemically with the stratum of fusible material in the heat exchange unit. The stratum of fusible material may consist of any suit able refractory material, such as tungsten or carbides for reducing gases, or various oxides or nitrides for oxidizing gases, or any other material capable of producing gas temperatures in the range of 8,000 F. to l2,000 F. In addition, the means employed for melting the stratum of fusible material can be electrical, chemical or nuclear.

Referring to FIGS. 6 and 7 there is illustrated an embodiment of the invention utilizing nuclear energy as a heat source to melt the stratum of fusible material in the heat exchange unit. The embodiment includes a pressurized chamber 60, a heat exchange unit 61 rotatably mounted within the pressurized chamber, a drive assembly (not shown) similar to the drive assembly 12 described in connection with the embodiment illustrated in FIGS. 1 through 4, for rotating the heat exchange unit about its longitudinal axis, and a control system 62 for controlling the nuclear reaction of the heat exchange unit. The pressurized chamber 10 is provided with a cylindrical reflector wall 63 closed at both ends by end walls 64 and 65, and an inlet conduit 66 having a valve 67. A pressure gage 68 also is provided to indicate the pressure of the working fluid within the pressurized chamber.

The heat exchange unit 61 consists of a cylindrical rigid wall 69, a cylindrical inner stratum of a fissionable fuel-moderator material 70, providing an axial opening 71, a rear end wall 72 and a front end wall 73. The cylindrical wall 69 is disposed coaxially and has a smaller diameter relative to the wall 63 of the chamber, to provide a cylindrical space between the heat exchange unit and the cylindrical wall 63. The rear end wall 72 is spaced from the end wall 64, and is provided with an axial opening 74 therein which intercommunicates the interior of the pressurized chamber with the axial opening 71 of the heat exchange unit. The front end wall 73 is spaced from the front end wall of the chamber,

and is provided with an outlet conduit 75 passing through an axially disposed opening in the end wall 65. The outlet conduit 75 is connected at its outer end to a stationary conduit by means of a rotary coupling to intercommunicate the axial opening 71 in the heat exchange unit and the stationary conduit. The outlet conduit 75 passes through an axial opening in the end wall 65, in which there is mounted an annular seal to prevent leakage of working fluid within the pressurized chamber between the end wall 65 and the outlet conduit 75. The conduit 75, the stationary conduit and the coupling therefor, may be cooled either by the working fluid or by means of an external coolant supply system.

The heat exchange unit 61 is supported within the pressurized chamber by means of axially spaced support units 76 and 77. Each of such units includes an annular bearing race 78 having cylindrical bearings 79 on which an end of the cylindrical wall or shroud 69 is supported, and radially disposed struts 80 rigidly interconnecting the bearing race 78 and the cylindrical wall 63 of the pressurized chamber. lt will be appreciated, however, that the heat exchange unit 61 may be mounted for rotation within the pressurized chamber in any suitable manner.

The cylindrical wall or shroud 69 of the heat exchange unit is provided with a plurality of radially disposedopenings 81 about its periphery, registered with openings 82 in the inner stratum 70 of the heat exchange unit, to provide a plurality of passageways intercommunicating the interior of the pressurized chamber and the axial opening 71 of the heat exchange unit. It thus will be seen that working fluid under pressure, introduced into the interior of the pressurized chamber, will be caused to be injected substantially radially through registered openings 81 and 82, and axially through the opening 74 into axial opening 71. The working fluid in axial opening 71 will be discharged through outlet conduit 75 into the stationary conduit coupled thereto.

The control system 12 consists of a plurality of conventional drum-control rods 83 which are disposed in a plurality of longitudinally disposed, circumferentially spaced openings 84 in the reflector wall 63. The control rods 83 consist of a material which does not absorb neutrons readily, e.g., aluminum or stainless steel, each having 90 to 180 of the cylindrical surface thereof coated with a material normally referred to in the nuclear reactor art as a poison," consisting of a material which absorbs neutrons copiously, e.g., boron or cadmium or their compounds. it will be noted that although 90 to 180 .of the surface of each control rod is coated with a poison material, the balance of the surface consists of a material which does not absorb neutrons readily. As illustrated in FIG. 6, the control rods 83 are adapted to be operatively connected to a drive mechanism so that the rods may be rotated about their axes to cause either the absorbing or nonabsorbing surfaces thereof to face the core of the heat exchange unit.

In the embodiment utilizing nuclear energy as a heat source, the heat exchange unit includes a metallic casing consisting of a material capable of withstanding cryogenic temperatures and maintaining the structural casing is provided with a plurality of openings for injecting the working fluid through the stratum of fuelmoderator material. The heat exchange unit is rotated at high speeds to contain the molten portion of the stratum of fusible material.

The working fluid utilized with the heat exchange unit preferably is a gas which does not react chemically with the fuel-moderator mixture, having a low molecular weight. Preferably, the fissionable fuel material is uranium carbide or dicarbide, and the neutron moderator material is a high temperature moderator material such as zirconium carbide or niobium carbide. The shroud of the heat exchange unit preferably is constructed of aluminum and is disposed in a matrix of neutron moderator material preferably consisting of an efficient low temperature moderator material, such as zirconium hydride or lithium hydride.

In the operation of the embodiment illustrated in FIGS. 6 and 7, the working fluid is introduced through the conduit 66 into the closed chamber under pressure. The heat exchange unit is then rotated and brought up to operating speed. When operating speed is attained, the reactor is activated to cause the inner surface of the stratum 70 to melt and the solid liquid interface to move radially outwardly to produce an inner liquid stratum and an outer solid stratum, until equilibrium between phases is established. As the working fluid traverses through the openings 81 in the metallic casing or shroud 69, it continues to flow through openings 82 in the outer solid stratum of the fuel material and is heated by the fission energy generated therein. The working fluid continues to flow radially inwardly and is heated as it bubbles inwardly through the liquid region of the stratum unitl it enters the center cavity or axial opening 71 of the unit, and recombines with working fluid injected axially through openings 74 into the heat transfer unit.

As is well-known, an operating nuclear reactor requires a high neutron flux in its core, so that sufficient neutrons are available to produce fission of the fissionable fuel material which may consist of uranium 235 or plutonium 239. In the operating condition, the bare surfaces of the control rods 83 are rotated to face inwardly toward the core of the heat transfer unit, as illustrated in FIG. 7. When it is desired to shut down the reactor, the rods are rotated so that their poison coated sides 85 face the core. By absorbing neutrons, the control rods damp down the reactor, in that they reduce the number of neutrons available for fission below the critical number needed to sustain the chain reaction. When it is desired to start up the reactor again, the rods merely are rotated so that their poison coated sides 85 face outwardly again, and the self-generation of neutrons by the fission process increases the neutron flux within the core of the reactor again until the chain reaction is self-sustaining. When a sufficiently large number of fissions occurs per unit time witliih the core of the reactor, their energy heats the stratum 70 of fissionable material to its operating level to melt the stratum.

It will be appreciated that the present invention provides several fundamental improvements over existing heat exchange systems, in that a molten heat source may be utilized to provide higher gas temperatures than other heat exchange systems, in the order of 8,000 F. to 12,000 F., the close thermal contact between the liquid and gas bubbles provides essentially percent heat exchange efficiency, and the high centrifugal field in which the bubles transverse to the center cavity of the heat transfer unit increases the bubble capacity sufficiently to provide total gas throughput rates at least an order of magnitude greater than those of conventional one-gravity liquid-bed heat exchangers.

From the foregoing detailed description it will be evident that there are a number of changes, adaptations and modifications of the present invention which come within the province of those skilled in the art. However, it is intended that all such variations not departing from the spirit of the invention be considered as within the scope thereof as limited solely by the appended claims.

I claim:

l. A heat exchanger comprising a mass of fusible material, means for melting at least a portion of said fusible material, means for applying a force on said mass of material when at least a portion thereof is in a molten state to maintain the physical integrity of said portion of molten material, means for injecting a first portion of a working fluid through said portion of molten material and means for passing a second portion of said working fluid along a surface of said portion of molten material and means for discharging said working fluid.

2. A heat exchanger according to claim 1, wherein said mass of material is of a type which is nonreactant with said working fluid.

3. A heat exchanger according to claim 1, wherein said melting means is electrical.

4. A heat exchanger according to claim 1, wherein said mass of fusible material comprises a fissionable fuel-moderator material and said melting means comprises means for activating said fissionable material.

5. A heat exchanger according to claim 1, including means for cooling a portion of said mass of fusible material, cooperating with said force for retaining the physical integrity of said portion of molten material.

6. A heat exchanger comprising a mass of fusible material, means for melting at least a portion of said mass of material, means for rotating said mass of material to maintain the physical integrity of said molten portion of said mass of material by centrifugal force whereby an axial passageway is formed therein, means for injecting a fluid through said rotating molten portion of said mass of material and means for injecting a working fluid through said axial passageway in said rotating molten portion of said mass of material.

7. A heat exchanger according to claim 6, wherein said mass of fusible material is of a type which is nonreactant with said working fluid.

8. A heat exchanger according to claim 6, wherein said melting means is electrical.

9. A heat exchanger according to claim 6, wherein said mass of fusible material comprises a fissionable fuel-moderator material and said melting means comprises means for activating said fissionable material.

B0. A heat exchanger according to claim 6, including means for cooling a portion of said mass of fusible material, cooperating with the centrifugal force acting on said mass for maintaining the physical integrity of said molten portion of said mass of material.

ll 1. A heat exchange system comprising a plurality of heat exchange units, each heat exchange unit comprising a mass of fusible material, means for melting at least a portion of said mass of fusible material, means for rotating said mass of material to maintain the physical integrity of said molten portion of said mass of material,

providing an axial passageway therein, means for injecting a working fluid through said rotating molten portion of said mass of material and means for injecting a working fluid axially through said rotating molten portion of said mass of material.

12. A heat exchanger comprising a closed chamber, means for injecting a working fluid under pressure into said chamber, at least one rotatable unit mounted in said chamber, said unit including a rigid cylindrical outer wall and a cylindrical inner stratum of fusible material, providing an axial opening through said unit having one end thereof communicating with the interior of said chamber and the other end thereof communicable with outlet means, said outer wall and inner stratum having a plurality of radial openings intercommunicating the interior of said chamber and the axial opening of said unit defining passageways for working fluid introduced into said closed chamber, means for melting the inner portion of said inner stratum and means for rotating said unit about its cylindrical axis whereby when said inner portion of said stratum of fusible material is in the molten state, its physical integrity will be maintained by centrifugal force while a first portion of the working fluid introduced into said chamber is injected through said radial openings and said rotating molten mass of material, and a second portion of said fluid flows through said axial opening.

13. A heat exchanger according to claim 12, wherein said stratum of fusible material is of a type which is nonreactant with said working fluid.

14. A heat exchanger according to claim 13, wherein said melting means is electrical.

15. A heat exchanger according to claim 12, wherein said stratum of fusible material comprises a fissionable fuel-moderator material and said melting means comprises means for activating said fissionable material.

16. A heat exchanger according to claim 12, including means for cooling a portion of said stratum of fusible material, cooperating with said centrifugal force for maintaining the physical integrity of the inner molten portion of said stratum of fusible material.

17. A heat exchanger according to claim 12, wherein said melting means includes at least one electrode disposed in heat transfer relation with said stratum of fusible material and an electrical supply circuit.

18. A heat exchanger according to claim 17, wherein said electrode includes an internal passageway for circulating a coolant therein.

19. A heat exchanger comprising a closed chamber, means for injecting a working fluid under pressure into said chamber, at least one rotatable unit mounted in said chamber, said unit including a rigid cylindrical outer wall and a cylindrical inner stratum of fusible material, said outer wall and inner stratum having a plurality of radial openings intercommunicating the interior of said chamber and an axial outlet opening in said unit,

defining passageways for working fluid introduced into said closed chamber, electrical means for melting the inner portion of said stratum of fusible material and means for rotating said unit about its cylindrical axis whereby when said inner portion of said stratum of fusible material is in the molten state, its physical integrity will be maintained by centrifugal force while said working fluid introduced into said chamber is injected through said radial openings and said rotating molten mass of material, and exhausted through said outlet opening.

20. A heat exchanger according to claim 19, wherein the electrical means for melting the inner portion of the stratum of fusible material comprises at least one electrode having an electrical supply source, embedded in said stratum of fusible material.

21. A heat exchange method comprising melting at least a portion of a mass of fusible material, exerting a force on said mass of fusible material to maintain the physical integrity of the molten portion thereof, injecting a first portion of a working fluid through the molten portion of said fusible material and passing a second portion of said working fluid along a surface of the molten portion of said fusible material.

22. A heat exchange method comprising melting the solid-liquid interface in said stratum of fusible material. III =l 

1. A heat exchanger comprising a mass of fusible material, means for melting at least a portion of said fusible material, means for applying a force on said mass of material when at least a portion thereof is in a molten state to maintain the physical integrity of said portion of molten material, means for injecting a first portion of a working fluid through said portion of molten material and means for passing a second portion of said working fluid along a surface of said portion of molten material and means for discharging said working fluid.
 2. A heat exchanger according to claim 1, wherein said mass of material is of a type which is nonreactant with said working fluid.
 3. A heat exchanger according to claim 1, wherein said melting means is electrical.
 4. A heat exchanger according to claim 1, wherein said mass of fusible material comprises a fissionable fuel-moderator material and said melting means comprises means for activating said fissionable material.
 5. A heat exchanger according to claim 1, including means for cooling a portion of said mass of fusible material, cooperating with said force for retaining the physical integrity of said portion of molten material.
 6. A heat exchanger comprising a mass of fusible material, means for melting at least a portion of said mass of material, means for rotating said mass of material to maintain the physical integrity of said molten portion of said mass of material by centrifugal force whereby an axial passageway is formed therein, means for injecting a fluid through said rotating molten portion of said mass of material and means for injecting a working fluid through said axial passageway in said rotating molten portion of said mass of material.
 7. A heat exchanger according to claim 6, wherein said mass of fusible material is of a type which is nonreactant with said working fluid.
 8. A heat exchanger according to claim 6, wherein said melting means is electrical.
 9. A heat exchanger according to claim 6, wherein said mass of fusible material comprises a fissionable fuel-moderator material and said melting means comprises means for activating said fissionable material.
 10. A heat exchanger according to claim 6, including means for cooling a portion of said mass of fusible material, cooperating with the centrifugal force acting on said mass for maintaining the physical integrity of said molten portion of said mass of material.
 11. A heat exchange system comprising a plurality of heat exchange units, each heat exchange unit comprising a mass of fusible material, means fOr melting at least a portion of said mass of fusible material, means for rotating said mass of material to maintain the physical integrity of said molten portion of said mass of material, providing an axial passageway therein, means for injecting a working fluid through said rotating molten portion of said mass of material and means for injecting a working fluid axially through said rotating molten portion of said mass of material.
 12. A heat exchanger comprising a closed chamber, means for injecting a working fluid under pressure into said chamber, at least one rotatable unit mounted in said chamber, said unit including a rigid cylindrical outer wall and a cylindrical inner stratum of fusible material, providing an axial opening through said unit having one end thereof communicating with the interior of said chamber and the other end thereof communicable with outlet means, said outer wall and inner stratum having a plurality of radial openings intercommunicating the interior of said chamber and the axial opening of said unit defining passageways for working fluid introduced into said closed chamber, means for melting the inner portion of said inner stratum and means for rotating said unit about its cylindrical axis whereby when said inner portion of said stratum of fusible material is in the molten state, its physical integrity will be maintained by centrifugal force while a first portion of the working fluid introduced into said chamber is injected through said radial openings and said rotating molten mass of material, and a second portion of said fluid flows through said axial opening.
 13. A heat exchanger according to claim 12, wherein said stratum of fusible material is of a type which is nonreactant with said working fluid.
 14. A heat exchanger according to claim 13, wherein said melting means is electrical.
 15. A heat exchanger according to claim 12, wherein said stratum of fusible material comprises a fissionable fuel-moderator material and said melting means comprises means for activating said fissionable material.
 16. A heat exchanger according to claim 12, including means for cooling a portion of said stratum of fusible material, cooperating with said centrifugal force for maintaining the physical integrity of the inner molten portion of said stratum of fusible material.
 17. A heat exchanger according to claim 12, wherein said melting means includes at least one electrode disposed in heat transfer relation with said stratum of fusible material and an electrical supply circuit.
 18. A heat exchanger according to claim 17, wherein said electrode includes an internal passageway for circulating a coolant therein.
 19. A heat exchanger comprising a closed chamber, means for injecting a working fluid under pressure into said chamber, at least one rotatable unit mounted in said chamber, said unit including a rigid cylindrical outer wall and a cylindrical inner stratum of fusible material, said outer wall and inner stratum having a plurality of radial openings intercommunicating the interior of said chamber and an axial outlet opening in said unit, defining passageways for working fluid introduced into said closed chamber, electrical means for melting the inner portion of said stratum of fusible material and means for rotating said unit about its cylindrical axis whereby when said inner portion of said stratum of fusible material is in the molten state, its physical integrity will be maintained by centrifugal force while said working fluid introduced into said chamber is injected through said radial openings and said rotating molten mass of material, and exhausted through said outlet opening.
 20. A heat exchanger according to claim 19, wherein the electrical means for melting the inner portion of the stratum of fusible material comprises at least one electrode having an electrical supply source, embedded in said stratum of fusible material.
 21. A heat exchange method comprising melting at least a portion of a mass of fusible material, eXerting a force on said mass of fusible material to maintain the physical integrity of the molten portion thereof, injecting a first portion of a working fluid through the molten portion of said fusible material and passing a second portion of said working fluid along a surface of the molten portion of said fusible material.
 22. A heat exchange method comprising melting the inner portion of a cylindrical stratum of fusible material, rotating said stratum of fusible material about its cylindrical axis to maintain the physical integrity of the molten portion of said stratum of fusible material by centrifugal force, injecting a working fluid radially through the molten portion of said stratum of fusible material and injecting working fluid axially through said cylindrical stratum of fusible material.
 23. A heat exchange method according to claim 20, including cooling the outer portion of said cylindrical stratum of fusible material to maintain a predetermined solid-liquid interface in said stratum of fusible material. 